import React, {Component} from 'react';

export default class Footer extends Component {

    //全选checkbox的回调
    handleCheckAll=(event)=>{
        this.props.checkAllTodo(event.target.checked)
    }

    //清除所有已完成的回调
    handleClearAllDone=()=>{
        this.props.clearDone()
    }

    render() {
        const {todos} = this.props

        //计算已完成的个数
        const doneCount = todos.reduce((pre,todo)=> pre+(todo.done? 1:0),0)
        //计算总数
        const total = todos.length
        return (
            <div className="todo-footer">
                <label>
                    <input type="checkbox" onChange={this.handleCheckAll} checked={doneCount===total&&total!==0 ? true:false} />
                </label>
                <span>
                    <span>已完成{doneCount}</span> / 全部{total}
                </span>
                <button onClick={this.handleClearAllDone} className="btn btn-danger">清除已完成任务</button>
            </div>
        );
    }
}
